1. Field of the Invention
The present invention relates to an aluminium alloy cylinder and a method of manufacturing the same, more particularly to an aluminium alloy cylinder in which an iron layer is electrodeposited on the wall surface of a cylinder bore in the cylinder, and a method of manufacturing the aluminium alloy cylinder.
2. Description of the Prior Art
Today, aluminium alloy cylinder bodies are widely utilized, because the cylinder body is light in weight and superior in thermal conductivity, can be relatively easily manufactured by means of a sandmold casting process, permanent mold casting process or die casting, and has an adequate or sufficient strength. However, in order to apply such aluminium alloy cylinder to high power engines or two- or four-stroke engines, it is required to subject the wall surface of the cylinder bore to a surface treatment for the purposes of prevention of seizure or scoring and provision of a wear resistant surface.
It has been proposed as such surface treatments to electrodeposit or electroplate a hard metal, for example, such as chromium or the like on the wall surface of the cylinder bore. However, the electrodeposition for such metal requires long working time, and the finishing for the electrodeposited metal requires also long working time. In addition, the electroplating treatment of such metal is not preferable from the point of view of public pollution problem, because the electroplating effluents are extremely harmful. Furthermore, in the conventional cylinder with the hard metal being electroplated, it is difficult to maintain a continuous lubricant film on the sliding surface of the cylinder, and abrasive dust or metals produced from the wear or abrasion and extremely small solid hard materials coming from outside are retained on the sliding surface. This causes abrasion loss, seizure loss and scaffing or scoring loss between the sliding surface of the cylinder and the outer peripheral surface of a piston or piston ring thereon, and decreases the durability of the cylinder.
In order to maintain a continuous lubricant film on the sliding surface of the cylinder and to prevent the abrasive dust and extremely small external solid hard materials from remaining on the sliding surface, it has been proposed in the prior art to form projections of hard particles of microscopic size on the sliding surface, or inversely to form concaves of microscopic size to receive the abrasive dust and the extremely small external solid hard materials between the projections or in the concaves. However, these require precision machining and make difficult the manufacture of the cylinder.